The present invention relates to a bulb socket into which a bulb with a base is to be mounted.
Conventionally, as a bulb socket into which a bulb with a base is to be mounted, there is known a bulb socket of as shown in FIG. 8. This bulb socket includes a socket main body 61 which is formed of synthetic resin as an integral body and, on one end side of the socket main body 61, there is formed a bulb mounting hole 62 into which a bulb 60 can be mounted. A pair of securing grooves 63 are respectively formed at the two positions of the inner peripheral surface of the bulb mounting hole 62, while the two securing grooves 63 are spaced 180.degree. apart from each other. Each of the securing grooves 63 includes a guide portion 63a extending along the axial direction thereof and a bent portion 63b which is formed in the deepest end of the guide portion 63a such that it extends at right angles with respect to the guide portion 63; and, according to the shape thereof, the securing groove 63 is generally referred to as a J slot. Into the securing grooves 63, there can be engaged a pair of projections 65 which are respectively provided on the outer peripheral surface of a base 64 included in the bulb 60. And, on the bottom surface of the bulb mounting hole 62, there is mounted a positive side contact member 66 which is bent into an S shape. Also, the bulb mounting hole 62 includes a recessed portion 62a formed in the inner peripheral surface thereof, while a negative side contact member 67 is mounted in the recessed portion 62a such that it extends along the axial direction of the bulb mounting hole 62. Further, in the upper end portion of the negative side contact member 67, there is an elastic contact piece 68 formed by cutting and raising the present portion of the negative side contact member 67, while the elastic contact piece 68 is projected out from the recessed portion 62a.
In assembling the bulb 60 into the above-mentioned bulb socket, the projections 65 of the base 64 are pushed into their corresponding securing grooves 63 and, after then, the bulb 60 is rotated by a small angle to thereby cause the projections 65 to turn to the bent portion 63b side. As a result of this, the projections 65 are engaged with the bent portions 63b. Due to this, not only the bulb 60 can be mounted into the bulb socket such that it is prevented against removal, but also the positive side contact member 66 is elastically contacted with a positive side contact 69 provided on the leading end of the base 64 and the contact piece 68 of the negative side contact member 67 is elastically contacted with a negative side contact which is part of the outer peripheral surface of the base 64.
However, according to the structure of the above-mentioned conventional bulb socket, before the bulb with a base 60 is mounted into the bulb socket, if a tool such as a screwdriver or the like is erroneously inserted into the bulb mounting hole 62 of the bulb socket, then the tool might press against the contact piece 68 to push it deeper into the recessed portion 62a, thereby deforming the contact piece 68.
In addition to the above possibility, there is a fear that sufficient electrical connection cannot be secured between the contact piece 68 and base 64.